The purpose of this study is to evaluate and refine a new self-report instrument for the assessment of personality disorders and to examine the relationship between self-report and clinical assessment of personality. The Personality Diagnostic Questionnaire (PDQ) is a 152-item, True/False questionnaire, the items of which are keyed to the new Third Edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-III). A large group of psychiatrists will each be asked to administer the PDQ to two patients they are currently treating. One of the patients will be selected for having prominent personality pathology that meets DSM-III criteria for at least one personality disorder or mixed personality disorder. The second patient selected will not have any prominent personality pathology. For each of these two patients, the psychiatrist will make DSM-III Axis I and Axis II diagnoses, as well as a scaled judgement of severity of personality disturbance. From the data obtained from the PDQs and the clinicians' assessments the investigators will do the following: 1) A PDQ index of personality disturbance will be constructed. 2) PDQ Axis II diagnoses will be compared to clinicians' Axis II diagnoses. 3) A factor analysis will be performed to examine the relationship of the factor structure to the eleven categories and three clusters of personality disorders specified in the DSM-III. An instrument that can yield DSM-III personality disorder diagnoses is likely to find widespread use by clinicians, researchers, and epidemiologists. It is expected that the PDQ will be a useful instrument for screening for personality disorder in many settings. Identification of groups homogeneous for specific personality disorder diagnoses would then permit closer study of the course, treatment response and familial pattern of these disorders.